HOW TO BUILD A MODEL LOCOMOTIVE.
As a preparatory step toward becoming an engineer, it is highly
desirable for the boy who looks forward to that honorable calling to
familiarize himself with the different parts of the locomotive engine.
This we have stated before.
There is no better way to accomplish it than to build a model
locomotive.
At first glance this may seem to be among the things impossible, but it
is not so, providing the boy has a mechanical turn, and any boy who has
not better not think of becoming an engineer.
We now propose to give simple and accurate directions for building a
model locomotive, accompanying the same with a series of illustrations,
which we trust will be sufficient for the purpose intended.
Before beginning we have one word of caution to offer.
Don't do your work in a hurry. Don't calculate on the length of time
it is going to take you to do it. Make up your mind to understand each
detail before you begin, and to work slowly and carefully.
If you remember this you will probably be able to build your
locomotive. If you forget it you certainly will fail.
HOW TO BEGIN.
First of all in building a model locomotive, as in every other class of
engineering work, it is necessary to get the measurements correct in
spacing out the different parts to be joined together; and do not think
that because it is only a model you are making that any off-hand way
will do, because you will find before the engine is half finished that
great accuracy is necessary if you wish your model to work.
A slight mistake in the measurements of a large engine will cause so
much friction as to take half its power to overcome. The same mistake
with your model will stop it entirely.
In soldering be careful to get the metal thoroughly heated. You will
then get a firm joint--otherwise not.
[Illustration: Fig. 1.]
[Illustration: Fig. 3.]
[Illustration: Fig. 4.]
[Illustration: Fig. 6.]
In giving these directions we assume that the boy who will undertake to
follow them is accustomed to the use of tools to some extent. If not,
he will have to learn as he advances by repeated experiments.
Try your experiments on something else. In soldering, for instance,
solder pieces of brass together until you learn to make a joint.
Don't try your experiments on your model, or you will grow discouraged
before you are half through.
A word more about soldering.
Do not touch the metal with the soldering-iron and then take it away.
You might be able to solder in that way but the joint would not hold,
but fall apart at the first pressure or slight blow.
Soldering on the best work should be used very seldom, and all the
fastenings should be either done by riveting, screwing or brazing, and
it is hardly necessary to remark that no part of a boiler should be
soldered which comes in contact with the flame of the lamp or furnace.
Brazing had better not be attempted by any boy who has not been
practically taught the art, unless it be on small joints.
To braze the seams of a model boiler would require a forge fire, or a
very powerful gas blast--too expensive for the amateur. Small things
such as a broken slide valve, rod, etc., can be brazed by using a gas
blowpipe.
This will cost but little to make, and as it will be useful, we
explain. See Fig. 1.
To make a blowpipe such as is pictured in Fig. 1, first get a small
piece of brass tube, A, of about half an inch diameter, and 5 inches
long. Drill a hole at 2 inches from one end, and insert a piece of gas
pipe, B, soldering it in place.
Now take a glass tube a quarter of an inch in diameter and 7 inches
long, hold one end in a gas flame, and when red-hot draw it out to a
fine point, then file round and break off the tip, leaving a small hole.
Now take a sound cork and squeeze it into the tube A as at C, drill a
quarter inch hole through its center, insert the glass tube D, and the
blow pipe is finished.
To use it you connect the pipe B with a gas bracket by means of a
rubber tube, and attach the glass tube D to a pair of bellows by means
of another piece of rubber tubing. The bellows should have an air-bag
attached. Otherwise you will have a jerky, uncertain flame.
When you want to braze any article, bind the parts together with some
very fine brass wire and cover with a little powdered borax and water;
then lay the article on a piece of charcoal, and if it is necessary to
preserve the temper of the steel you are about brazing, cut a potato
in half and push each end of the steel rod into the halves, which will
keep the temperature from getting too high.
Then turn on the gas and start your blow pipe, at the same time
working the bellows with your foot, and by either pushing in the glass
tube D, or drawing it slightly out, you can regulate the shape of the
flame as required.
[Illustration: Fig. 2.]
[Illustration: Fig. 5.]
[Illustration: Fig. 7.]
[Illustration: Fig. 8.]
[Illustration: Fig. 11.]
[Illustration: Fig. 12.]
Now bring the flame to bear on the joint you wish to braze, having
first supplied plenty of borax. Soon you will find the brass wire
melting and running into the joint like water. It must then be neatly
filled up and the joint will be scarcely visible.
Here are a few tools which will be useful to you in this work.
A center punch, or steel spike for mashing metal for drilling, etc.,
and a small riveting hammer. Three or four files of different degrees
of fineness, a screw plate and taps, a small hand-drill with a set of
drills to fit and a good firm vise.
A lathe is of course desirable. Curves for bending metal you can easily
make from pieces of bar-iron, holding them in the vise while working on
them.
When you have your tools ready get the material for your model.
Several sheets of brass and copper, the castings and various sized
screws and bolts are what will be required.
All being thus prepared the time has arrived to take the
FIRST STEP.
The first step toward building a model locomotive is to be posted on
the action of steam in the cylinder.
Go to encyclopedia and read up on that point.
If you have no encyclopedia go and look one up in some library. You
can't build your engine until you understand this.
Next draw an accurate plan of your model.
Figure 2 is the idea. It is a side view of our locomotive. Let us
describe.
A. Boiler.
B. Smoke-stack.
C. Screwhead, to fill boiler with water.
D. Steam chest with safety valve attached on top.
E. Whistle.
F. Steam tap to start the engine with.
H. H. Leading and trailing wheels.
I. Driving wheel.
K. Cylinders.
L. Frame.
M. Buffers.
N. Set thumbscrew to fasten on the tender.
O. The lamp.
P. Tap, used to ascertain the quantity of water in the boiler.
R. S. Hand rail.
To all locomotives there are three principal parts, the frame work, or
carriage, the engine, or cylinders, and parts connected with them, and
the boiler.
Our model shall be a fifteen inch one.
LAYING OUT MATERIALS
is the next thing in order. First we want a sheet of brass for the bed
plate, 1/16th of an inch thick, cut 4×14 inches, and be sure to cut the
corners square. (See Figure 3.)
Hammer this out flat, file it smooth and dress up, with emery cloth
fastened upon a flat piece of wood.
Next cut a square hole in it as at C, beginning half an inch from B,
and making the opening 11 × 1-1/2 inches. Be careful to center this
hole on the line A B, or your engine will be lopsided, and you must
take the same care in setting the smoke stack, dome, etc.
Now take Fig. 4. This represents one of the side frames. Cut these out
now, thus:
Drill holes at A B C for the axles to work in. Finish both sides the
same way. Turn the bed plate upside down, fasten the frames on at a
quarter of an inch from either side by small angle pieces (Fig. 5), or
by soldering, which is easier done. Then solder a piece across each
end, about half an inch deep, and the frame is ready for the wheels.
These you can make if you have a lathe, but it would be better to buy
your wheels ready made if you can, but if you can't do that, and have
the lathe, turn your tires up to the form shown in Fig. 6.
The small wheels should be about 2-1/2 inches in diameter, and the
driving wheels, 4 inches. The rim, B, should project a little over
1/16th of an inch, and the rest of the edge should be beveled off
rightly, as at A.
The spokes should then be filed up smooth, drilling out the center hole
for the axle before removing it from the lathe.
Great care must be taken to turn both the driving wheels to exactly
the same diameter, or one wheel would travel further in a revolution
than the other, and as they ought both to be fixed rigidly on the crank
shaft, the engine would never travel in a straight line, but would go
round and round in a circle.
Get some steel wire for the axles and fasten them to the wheels by
soldering or by cutting a slot with a fine file in the center of the
wheel, as at A, Fig. 7. Then file a small portion of the ends of the
axle flat and drive in a brass wedge made by a piece of wire which will
hold them together firmly.
The crank shaft, or axle, must be hammered up to shape, making it hot
occasionally in the gas flame while working it.
The cranks should be at right angles to each other, and the throw of
the crank half the distance of the cylinder stroke.
For instance, say the cylinder being a 1-1/2 inch stroke, the distance
between A B (Fig. 8) will be three-quarters of an inch, you must then
ease the size of the crank at A to prevent the piston knocking the
cylinder ends.
[Illustration: Fig. 9.]
The cylinders you had better buy ready made or have them made for you.
Get a pair of oscillating cylinders of three-quarter inch bore and inch
and a half stroke. These will drive your engines several miles an hour.
Fig. 9 gives an underneath view of the frame work and the place to put
the cylinders in. They must be supported by two lugs, A A, screwed to
the bed plate B, which must have a piece cut out on either side to
allow the driving wheels C, to work in, as at D; because, being larger
than the others, they project beyond the top of the bed plate, as shown
in Fig. 2.
Next screw on by means of the hook F, the buffer beam, previously cut
from a piece of mahogany, 5 inches long, half an inch thick and one
inch deep, nicely squared and sand papered. Drill a hole at G, and pass
the shank of the hook through the beam and piece of brass in front of
the frame, screwing up tight with nut H.
For buffers you may take two brass, flat-headed screws, and attach
them to the beam half an inch from either end, allowing half an inch
projection.
Now polish everything smooth and bright. Next warm the model over the
gas--don't let it get hot--and carefully lacquer it with a small brush
taking care not to go over any part more than once. The spokes of the
wheels must be painted, the buffer beams varnished and the cylinders
painted, leaving the covers and flanges bright. Now put away your work
to dry, covering carefully from dust.
HOW TO MAKE THE BOILER.
In making the boiler you can't be too careful. This is the part where
the greatest chance for failure comes in.
Buy a piece of copper tubing 11 inches long, 3 inches wide and half an
inch in diameter.
If you want to make it yourself bend your copper round a wooden roller
and rivet or solder together--riveting is the best if you can get it
tight. You must then turn two circles of brass about an eighth of an
inch thick for the ends and polish all. Fig 10 gives you the idea.
Now push the ends into either end of the tube about an eighth of
an inch from the edge, as at A, Fig. 11, and solder in place. The
projecting flange must be hammered down all around as at B, soldered
and finished with a half round file. When filing solder use only an old
worn file as a good one soon fills up.
SMOKESTACK, TUBES, ETC.
Now drill a hole at A (Fig. 10) for the smokestack, which should be
three-quarters of an inch in diameter. Then cut a slot in the bottom of
the boiler 6 inches long by 1-1/2 inches wide, commencing one-quarter
of an inch from the forward end of the boiler.
[Illustration: Fig. 10.]
[Illustration: Fig. 13.]
[Illustration: Fig. 14.]
[Illustration: Fig. 15.]
[Illustration: Fig. 16.]
Next take a sheet of copper and cut a piece about 6-1/4 inches long
by 6 inches wide and bend it over a wooden roller to the shape shown
in Fig. 12, keeping it 1-1/2 inches apart between A and B. Cut also
two other pieces of copper to the shape of your bent sheet (Fig. 12),
and make it long enough to reach to the dotted line. These form the
two ends, and may be placed an eighth of an inch from the edges, as in
Fig. 13, and soldered in place, and the projecting rims turned over and
sweated with solder from the outside, in the same manner that you did
the boiler ends in Fig. 11. Then drill a three-quarter inch hole at B
(Fig. 13) for the bottom of the smokestack to go into, and cut a piece
of three-quarter inch brass tubing of sufficient length to pass out at
top of boiler about half an inch, as shown at A, Fig. 10. You can then
hammer out a rim or flange on the bottom end of the smokestack and push
it up through the hole in the copper box, soldering it in place from
the top as at A, Fig. 14. Then drill two small holes at each end of the
box, B C, Fig. 14. These should be a little more than an eighth of an
inch in diameter, to allow an eighth of an inch tube to pass through.
Now get two 12-inch lengths of hard drawn steam pipe, an eighth of an
inch in diameter, and with your screw plate put a thread on each end,
about half an inch in length. Then make eight nuts to fit the threads
on the piping, filing them up into proper shape.
Now take the piping and bend it very gently, to prevent it cracking,
around a bar of iron or handle of some tool held in the vise, until
it is in the form shown in Fig. 15. Do each one the same, then mix a
little turpentine with white lead, and smear each end, where you have
formed the screws, taking care not to get any into the tubes, which can
be temporarily plugged up.
Next put a nut at either end, as far as the thread will take it, then
smear a little white lead around the holes drilled in the ends of the
box, B C, Fig. 14.
Push the tubes in from the inside, and screw up firmly with the
remaining nuts, in the position shown at Fig. 16. The inside nuts can
then be tightened up with a wrench, and if you do all this carefully,
you will never be troubled with any leakage, no matter what pressure
you may get in your boiler.
These tubes are immensely strong, and owing to their small size, the
water in them is raised quickly to a higher temperature than that
contained in the rest of the boiler, causing a continual circulation to
take place, and a constant supply of steam to be found.
The box can now be placed in the boiler, through the slot cut in the
bottom, taking care that the top of the box is not more than half way
up the boiler, as at B, Fig. 10. This will leave a portion projecting
below the lower edge of boiler like C. This part protects the flame
of the lamp from being blown away by the draught caused by traveling
along, and which would cause you to lose steam. Solder it firmly in
position from the outside to prevent the flame from touching any
soldered portion. Also solder neatly round A, Fig. 10.
The smoke stack can be made from another piece of three-quarter inch
brass; turn it up in your lathe bright and put a collar on it at A Fig.
17, to allow it to push on to the piece of tube left projecting at A
Fig. 10.
The top of the smoke stack, B Fig. 17, will also require turning in the
lathe and must be fitted on neatly.
Get advice from some mechanic about the steam chest, which is a brass
casting and will have to be turned up in the lathe, and after cutting a
circular hole in the top of the boiler of about an inch in diameter it
can be either screwed or soldered on, previously putting the steam pipe
E in position by drilling a hole at F and after bending it as shown,
pass it through at F and solder in place. The top of pipe E should be
about a quarter of an inch from the top of inside of steam chest.
Before soldering on the steam chest drill two holes as at G H Fig. 10,
one for the small lug G to be screwed into, which holds one end of the
lever of the safety valve, and that at H should be drilled conical with
a rimer, and the valve H can be turned in the lathe and afterwards
ground to fit the hole with a little emery and water, by means of a
slot cut across the top and worked round with a screw driver.
The spring case of the safety valve I, Figure 10, is easily made from
a piece of one-eighth inch brass tubing, using some small, hard, brass
wire to form the spring. When finished it should be hooked to the eye
and screwed into the boiler at V.
The manhole or screwhead, K, is used to refill the boiler when it has
steamed low and will have to be turned up to shape, and the bed, L,
which it screws into can be firmly soldered on the boiler, having first
drilled a hole slightly larger than the diameter of the screw itself,
which should be sufficiently large to allow an ordinary tin funnel to
be used to refill by, and the screw ought to be long enough to hold a
leather washer under the head to keep it steam-tight.
The whistle, M, will require a hole drilled for it to be screwed into,
and that, as also the steam-tap, N, and water-tap, O, can be bought
cheap, ready to put on.
The tap O should be screwed in at a slightly higher level than the top
of box B, and when working the engine should steam issue from it when
turned on instead of water, you ought to immediately blow off steam by
safety valve H. Then unscrew K, and refill the boiler with water.
[Illustration: Fig. 17.]
[Illustration: Fig. 18.]
[Illustration: Fig. 19.]
[Illustration: Fig. 21.]
[Illustration: Fig. 22.]
By this time the framework will be quite dry, no doubt, so you can,
after cleaning and polishing the boiler, attach it to the frame by a
screw or solder at the forward end, and the steam-pipe N can be screwed
on to the projecting piece of tube left at F, while you also screw a
short length of pipe into the steam box of engine through a hole in the
bed plate. Then bend it up to the steam tap, and solder them carefully
in position; this will hold the after end of the boiler firm.
Go over every soldered joint to see if any small hole is left, and
resolder where necessary, as a hole in the boiler not larger than a
pin's point would prevent you from getting any pressure of steam in the
boiler, as the water would all blow out.
Now lacquer or paint your boiler, and while it is drying turn your
attention to the lamp, which we picture in Fig. 18.
THE LAMP.
The lamp is simply an oblong tin box, about 5 inches long by 1-1/4
inches wide and three-quarters of an inch deep.
To make it cut a piece of tin 4-1/2 by 5 inches and bend it to shape.
Then solder the two edges together and cut two ends to fit; push them
in and solder in place.
Now cut three pieces of brass quarter-inch tubing into three-quarter
inch lengths; drilling holes in top of lamp, insert them, allowing a
quarter of an inch to project, as at A, Fig. 17. Then solder them on
four pieces of bent wire--C, C, C, C, Fig. 18--by which to hang the
lamp by means of two wire pins run through them and small holes drilled
in the sides of projecting piece C, Fig. 10.
The screw filler B, Fig. 18, will have to be soldered in, also, and
when complete the tubes A may be filled with cotton wick and the lamp
about three-parts full of a methylated alcohol, which will give a
clear, smokeless flame.
Now you can start your locomotive by filling the boiler about three
parts full of hot water, and then hooking the lamp underneath; you will
soon get up a good pressure of steam.
See that the taps are all turned off, and if there is no leakage from
careless workmanship, you will find on turning the steam tap on, that
the locomotive will run beautifully and will travel at great speed
either on a smooth oil-cloth or a board floor.
On rails it would run quicker still, but for this engine, if you make
a small tender of the shape shown in Fig. 19, and fasten it at any
angle by the set-screw on the foot-plate of the engine shown at N, Fig.
2, the model will run in any sized circle you may wish without rails,
according to the angle you fix the tender to the engine.
Wooden cars you can make if you wish, but each one added will reduce
the speed of the engine, of course.
Tin is the best material to use for the tender, as no great strength is
required--indeed it should be made as light as possible. The wheels
and axles you must finish in the same manner as those on the engine,
and it can be made into a tank to hold an extra supply of alcohol by
soldering a piece of tin round the inside and covering it in with
another piece cut to shape and fitted with a screw nut to fill by as
shown in Fig. 18.
Such is the method of constructing a model locomotive which will run
without complicated machinery.
The boy who has succeeded in following these directions will no doubt
be ambitious to try his hand on a more complete model on a larger
scale, something like Fig. 20 for instance, which is a side view of a
large model locomotive in a finished state.
HOW TO BUILD A LARGE MODEL LOCOMOTIVE.
In building a large model the first thing to be done is to decide
how large you want it. Sketch your model carefully, or, if not able
to draw plans, get some one who is to help you. Make your plan the
exact size of the model you intend to build, then you can take all the
measurements from it and save yourself a lot of trouble and time.
Remember, however, that the larger you make the engine the more
expensive the castings and materials will be.
Should you persevere, however, and by good fortune succeed, you will
have a model locomotive that would cost you two or three hundred
dollars to buy ready made. If you have a lathe and can turn the wooden
models for the castings yourself, use sheet iron for the frame-work,
etc., where possible; the total expense will not be so very great.
Begin your work in the same way you did on the other model. If you
want a bigger engine than the one shown in Fig. 20, there would be no
trouble in increasing the measurements, which we are about to give,
proportionately, remembering that Fig. 20 is drawn to an eighth-inch
scale.
DIMENSIONS.
Make your dimensions as follows: Length over all, 3 ft. 2 in. Length
of bed-plate, 3.5 in. Width of bed-plate, 9 in. Diameter of driving
wheels, 8-1/4 in. Diameter of leading wheels, 5-1/4 in. Gauge--that is
width of track on which model can run--6-1/2 in. Cylinders, 1-3/4 in.
bore by 2-1/2 in. stroke. Length of boiler, including smoke box, 28 in.
Diameter of boiler, 5 in.
Cylinders of the above dimensions will drive the engine at a high rate
of speed, with from 30 to 50 lbs. of steam.
DESCRIPTION OF LARGE MODEL LOCOMOTIVES.
In Fig. 20, the different parts of the engine are lettered, and it
will be well for the boy who desires to make a locomotive like it to
compare the following description with the cut, before he does anything
else.
[Illustration: Fig. 20.]
A is the smoke stack and B the steam blast used to increase the
intensity of the fire worked by rod C running through the hollow
hand-rail D and ending in handle F. G is the steam-dome, which with the
safety valve is the same pattern previously used. H is the extra safety
valve, worked from the foot-plate. I is the steam whistle, K wind
guard, L starting lever, M smoke-box with door, N O spring buffers;
P is the line-clearer or wheel guard. Q are the leading wheels, R R
the driving wheels, S is one of the cylinders with piston rods and
guides bolted to frame and showing double connecting rod at T T. U U
are the springs which support the weight of the boiler, etc., on the
axle bearings. The spring or rear wheel does not show, being inside the
safety guard and hand-rail V. W is the back pressure valve, through
which the water is thrown by the force-pump into the boiler, and X is
the blow-off tap to clear the engine from all water after having used
it. Y shows the side of the ash-pan.
HOW TO DO THE WORK ON THE LARGE MODEL LOCOMOTIVE.
First of all comes the frame work. It wants to be of eighth inch sheet
iron squared up perfectly true and flat and cut as is shown in Fig. 21,
beginning 4-1/2 inches from A, and leaving 6 inches at B, and cutting
it 6 inches wide there by 8 inches long, and continuing it 4 inches
wide for the rest of the distance. Be careful to keep it quite central
on the line A B, and leave two connecting strips 1 inch wide as at C C.
The side frames come next. These must be much stronger and quite
different from those used in the previous model. They may be cut from
the same eighth inch iron to the shape shown in Fig. 22.
The center of slot B is 17 inches from one end, the center of A 10
inches from B, and the center of C 13 inches from B.
In measuring, always start from a given center if you want to be
accurate. That is, from B to A and from B to C; not from B to A and
from C to B.
The slots are each 1-1/4 inches wide by 2 inches deep, leaving 1 inch
of iron at the top, as shown. The four large boles shown in Fig. 23 are
only ornamental, and can be now cut out. They also serve to lighten the
frame.
The frames, after being smoothed up can be fastened to the bed plate in
the manner described before, by angle-irons, or knees, riveted on.
Two end pieces must also be prepared. Let them be 1 inch deep, with the
ends hammered square, at right angles, and then riveted to the bed
plate and side frames, as shown in Fig. 20. Then drill three holes in
them, about an inch and a half from either end, and one in the center,
by which to bolt on the buffer beams by means of a couple of screws put
in at the back. The buffer beams should be mahogany, 1 inch wide by 2
deep by 10 long, squared nicely and sandpapered. A hook can then be
made--Fig. 23--and a hole being drilled in the center of the beam, you
can pass the hook stem through and into the central hole of framework,
and screw up tight with nut at back, which will hold all firmly in
place. The buffers for this model must be properly made, with springs
to take the pressure in case you should run into anything.
Fig. 24 shows this buffer. You will have to get it cast. Turn out in
your lathe a wooden mold and get four castings in brass made from it. A
Fig. 24 is cast with a square base plate 2 inches square, as in front
view B, and is secured to the buffer beam by four flat-headed screws.
The piece C must be turned true and just the size to slide in and out
of A easily. Each part must be finished up in the lathe. A should be an
inch and a half long. Drill a hole in the buffer beam to allow the head
of the pin to work freely, and another hole in base plate of buffer the
size of the pin, whose head prevents the spring from forcing C entirely
away from A.
The spring should be made of thick steel wire; the buffers can then be
screwed in as just mentioned. The wheel-guard or line-clearer P (Fig.
20) can next be cut out to shape and bolted on to frame, and should
just clear the line by a quarter of an inch.
We will now proceed to the axle bearings and springs, U, Fig. 20.
Make a wooden model like Fig. 25, and get 6 castings in brass made from
it. They must then be filed up square and smooth and fitted into the
slots cut at A, B, C, Fig 22, and either screwed or riveted on by the
side holes. Before finally fixing them prepare 6 brass bearings, B, Fig
25, which must fit exactly and slide easily in the inner surface of A,
then drilling a hole through each five-eighths of an inch in diameter.
These take the axles, which in this model are all straight, and
three-quarters of an inch in diameter, shouldered off to five-eighths
for the bearings.
Next for the springs. Take 4 pieces of either sheet iron or brass for
the supports, 1-1/2 inches long by 1/4 inch wide. Drill a hole in
either end as shown at C, Fig. 26. A should be three-eighths of an inch
wide, drilled through, a pin put in and all riveted together loosely.
[Illustration: Fig. 23.]
[Illustration: Fig. 24.]
[Illustration: Fig. 25.]
[Illustration: Fig. 26.]
Now take a clock spring and cut it into shape, as at D, Fig. 26. The
top piece requires to be made hot with your blow-pipe, then the ends
turned over to hold the pin B. Each piece of spring must be a little
shorter than the one above it, and the ends neatly tapered, all to be
inclosed in the brass band F, which has a small hole drilled at F to
hold the end of the pin by which the pressure is directed on to the
axle boxes, as shown in Fig. 20. A hole is also to be drilled in the
bed plate over the center of each axle box to allow the pin to pass
through, and also a smaller one an inch and a half on each side for the
support A, Fig. 26, to screw into. Now all can be fitted into position.
Next come the cylinders. These are to be an inch thick and
three-quarters bore by two and a half inch stroke. They should be of
the fixed slide-valve pattern, with double eccentrics fitted on the
middle axle shaft, and reversing lever brought to quadrant on foot
plate. They had better be bought ready made.
Fig. 27 shows their working. A A are the eccentrics, B the slide-valve
rod with guide G attached. C C is the bed plate and D the balance
weight, F the rod leading to quadrant and lever on foot plate. The
cranks are put on outside the wheels and fastened by keys as in Fig.
20. The connecting rod T should be cut to the form shown in Fig. 28,
and the ends squared out and a brass band fitted in with a hole drilled
from top A to oil by and a set screw B to adjust the bearings perfectly.
If you wish to fit a force pump it should be placed centrally between
the cylinders and be worked by an eccentric on the main shaft, but a
pump on a model locomotive is next to useless unless it is also made to
work by hand.
In Fig. 29, we have one which can be worked either way. A is the pump;
B the eccentric on main-shaft to work it by steam power. To work by
hand you have only to push up hook connection C, which disconnects it
from the eccentric; and then by working the handle D, which is screwed
into the bottom of the plunger C, the water is forced into the boiler.
An extra stuffing-box at F will be required. G is the exhaust water
pipe bent up to the back-pressure valve on boiler, and H the supply
pipe carried on to rear of engine.
Two small blow-off cocks will be necessary on each cylinder to get rid
of the condensed steam when starting. They can be connected with a
tye-rod, and both worked from the foot-plate with a single handle. Now
paint to suit your taste and put away to dry.
Next comes the boiler, which will need extreme care. For this you will
require sheet copper an eighth of an inch thick.
First cut a piece 19 inches long by 16 wide and bend it round, forming
a cylinder 5 inches in diameter. The cap must be closely riveted and
the two ends hammered out into a flange outward, leaving the body of
the boiler 17 inches long, as in Fig. 30. B is the shape of the piece
to be next riveted on at after end. Now take another sheet 9 inches
wide and hammer a half inch flange round it, so as to fit over the
dotted line at A. Rivet them firmly together and also another piece in
after end. It will then have the appearance of Fig. 31, and should be
4-1/2 inches deep from A to B, and forming a copper box 6 inches wide
from B to C and 8 inches from C to D. Then rivet together another box
to form the inner casing 4-1/2 inches wide by 6-1/2 inches long and 9
inches deep, the bottom to be hammered outward to the dimensions of B
C C D, as shown in section Fig. 32 at A A. A hole is next to be cut
out in the center of rear plate and also the rear part of inner casing
which comes opposite to it, and 1-3/4 inches by 2-1/2 forming the
furnace door.
A casting of that shape and 3/4 of an inch thick, which is the distance
between the inner and outer casing B C, must be procured and drilled
with holes every 3/8 of an inch and firmly riveted in position, as
shown in Fig. 32 at D. Two pins should project on either side of the
inner surface to support the fire-bars and ash pan, and the bars should
be made of cast iron and small enough to get out easily by tilting up
one side; they should run lengthwise of the engine.
For the boiler tubes some hard drawn brass tubing three-quarters of
an inch in diameter will be required. Cut the pieces slightly over
17 inches long, then drill 10 holes in the inner plate as at E, Fig.
32, and in the position and arrangement shown in Fig. 33. These tubes
should have a wire ring brazed on about a quarter of an inch from
either end, and then being placed in their respective holes in the tube
plate, the projecting portion is to be headed back with a flange, or
you can fit them in as already shown in Fig. 16 by each being double
screwed and nutted. These tubes allow the smoke and flame to pass
through from the furnace to the smoke box, M, Fig. 20, and so away up
the smoke stack, and by the large surface they expose to the fire, help
to raise steam very quickly. In some engines as many as 300 tubes are
fitted.
The steam supply pipe and regulating lever handle should now be made
and placed in position, and Fig. 34 shows the shape to make it. A B are
the front and rear plates of the boiler, C is the supply pipe bent with
a screw end downward, after passing plate A, and then upward into the
steam dome, where it should be securely fastened into a cross-piece. D
is the tap or valve which can be turned on or off from the foot-plate
by means of the long rod, F, ending in the lever handle, G.
The rod must be fitted with a stuffing-box, the same as those used on
the cylinders, and packed with cotton wick to prevent loss of steam by
leakage. When all this is complete, the forward end of the boiler can
be furnished with a tube-plate riveted on and the tubes flanged over.
Now the boiler must go to a practical brazier, and be properly brazed.
Cut the hole for the steam dome, and let him braze it on at the same
time. If the job is practically done, your boiler can be heated red-hot
without fear.
[Illustration: Fig. 27.]
[Illustration: Fig. 28.]
[Illustration: Fig. 29.]
Meanwhile buy your pressure gauge--it wants to be one and a half inches
in diameter--and let the brazier test your boiler to 100 pounds steam
to the square inch capacity.
Should it burst you will have to make another. If not you need
thereafter have no fears.
Now make the smoke box, which should be three inches deep and of the
shape and dimensions shown in Fig. 35. This and the smoke-stack can be
made of iron, hammered up to shape and finished with a brass ring. The
smoke-box can be screwed on the forward flange or boiler.
The door is drawn open to show the amount of bulge it should be
hammered to. In the center a hole should be drilled through which to
pass the screw used to close it, which is attached to the loose bar, A.
The handle, B, is then screwed up tight.
The door is circular and must be large enough to overlap the opening
about half an inch and have a couple of bright iron or brass eyes, C,
riveted on to form the hinge.
Next comes the back-pressure valve, Fig 36. A is a front view with
plate by which it is bolted to the boiler, as at W, Fig. 20.
It is very simple to make, and consists of the casting A with top and
bottom covers and the ball-valve B, which ought to be ground with a
little emery and oil to fit perfectly. It acts in this manner.
The water being forced up C from the pump, raises B and passes into the
boiler. On the up stroke of pump, the pressure is removed from under
B and the pressure of steam in the boiler causes it to fall back and
close the opening entirely, preventing any water from passing away from
the boiler. A small flange can be put on each outer side of the boiler
near the furnace to support it on bed-plate level with smoke box.
The boiler should now be covered with flannel, cut to shape and wrapped
round the body part and a casing of sheet tin put over it and secured
by brass bands and small nuts underneath--as shown in Fig. 20.
The steam supply pipe can now be connected with the cylinders and
it should be made forked as in Fig. 37. A leads from steam pipe and
branches off to each cylinder, where it must be screwed up with white
lead.
The exhaust pipes B B should be of larger tubing and bent round up the
sides of the smoke box so as to be out of the way when you have to
clean the tubes. A small brass pipe, C, must also be passed through the
chimney, bent upwards and fitted with a tap which should take the steam
from the top of the boiler and be used as shown at D F Fig. 20. This
helps to raise steam very quickly.
Fig. 38 is a rear view of the foot plate and shows the necessary
fittings which you must either make or buy to complete the model.
The cocks you might make but the water gauge you must buy. A is the
furnace door, B two gauge taps, C starting-lever handle, D spring
balance safety valve, F wind-guard with two look-out holes, G steam
whistle handle, H pressure gauge, N the quadrant and lever for
reversing the engine, O the rear buffer beam with buffers, P the wheels
showing axle, R R the springs for same and V the safety-guard rail on
either side.
[Illustration: Fig. 30.]
[Illustration: Fig. 31.]
[Illustration: Fig. 32.]
[Illustration: Fig. 33.]
[Illustration: Fig. 34.]
[Illustration: Fig. 35.]
[Illustration: Fig. 37.]
[Illustration: Fig. 36.]
When these fittings are all complete holes must be drilled in rear
plate for each piece; they must be firmly screwed in place with white
lead. The glass tube of the water gauge, the stuffing-box, and the
gland of the starting lever should be closely packed with tallow and
cotton wick.
[Illustration: Fig. 38.]
Next paint the entire model over again and let it dry. We give no
directions as to colors; use your own taste. After the paint is
thoroughly dry varnish with the best clear, hard varnish and let it dry
again.
While it is drying you can be making the rails.
Get some square bar iron, cut it into six-foot lengths, if you wish the
rails to be portable, and drill a hole in each end half an inch deep.
The rails can be joined together at each end by means of a piece of
wire and kept at a proper distance apart by being fastened to pieces
of wood placed like sleepers, fastened by screws passing through holes
drilled in the rails every six inches. These sections can be laid
end to end, and your line be made as long as you wish. If you want a
circular line, each section must be bent to a portion of a circle; one
about 30 feet in diameter is suitable for this model.
When finished place your locomotive on the track and get up steam. Fill
the boiler with water by means of a funnel until you see it rise up
three parts of the way in the glass water-gauge. Then see that all taps
are turned off and start the fire. Charcoal is the best fuel, as it
gives a clear, hot fire without much smoke once you start it right.
Try the safety-valve occasionally to see how your steam is getting on,
and when it begins to form turn on the blast-tap, which will soon draw
up the fire, and you will presently see the pressure rise and show
itself in the pressure-gauge.
When the gauge shows 30 lbs. of steam you might start the model by
turning on the cocks on cylinders until no more condensed steam issues
from them.
Then shut them off and turn on steam full power and watch the engine
travel, gradually increasing its speed.